NASA Schedules Space Walks to Fix ISS

Last week's efforts to fix a stuck valve on one of the International Space Station's two cooling loops from within the ISS have failed, NASA says. As a result, astronauts will undertake space walks beginning this weekend to repair the valve and get the station running at full speed once again.

NASA will outline it plans for the mission at 3 p.m. Eastern today, Dec. 18. In a statement last night, the agency said two astronauts will venture out on spacewalks on December 21, 23, and 25 to swap in a spare part.

As PopMech reported last week, the ISS had a problem with cooling loop A that NASA traced back to a control valve that mixes ammonia and coolant to the correct proportion, helping to prevent the system from freezing up. When it failed, operators had to shut down non-critical systems in multiple parts of the station. The astronauts on board are safe, as cooling loop B remains operational, but experiments could be in jeopardy as the second loop remains offline.

The pump module that contains the valve and needs to be fixed is on the outside of the ISS, requiring space walks to repair it. No problem for seasoned astronauts, except that a replacement for one of the spacesuits on the station, which was ruined when a leak nearly drowned an astronaut earlier in 2013, won't arrive in February. NASA would prefer to have a full complement of suits on board before sending astronauts outside the station, but this cannot wait.

One other casualty of the coolant problem: A planned launch of the Orbital Science Cygnus spacecraft. This was to be the first major cargo flight of the ship, which made its maiden voyage to the ISS in September. The mission is now delayed until at least mid-January.

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